when you said “unstable” do you mean the signal is continuously decreasing ?
or do you mean it is moving up and down, but the average is the same ?
regarding idle mode : measurement of rxlev is done only once every 5s. Therefore the measurements look more stable.
For dedicated mode, the refresh rate is much faster, showing all instantaneous variations.
DTX should not degrade the RxLev. Keep it activated.
A gradual decrease in dedicated mode is due to wrong power control parameters.
What are your values for
A LEV PC
A QUAL PC